Investigation of the chemical nature of the glycoprotein stimulated by addition of vitamin A to incubations of corneal epithelium in vitro and attempts to improve this stimulation by binding the vitamin to retinol-binding protein. The critical experiments will be done to determine whether the collagenase released from ulcerating vitamin A-deficient corneas is not inhibited by serum alpha 1-macroglobulin, whereas the collagenase from ulcerating (thermally burned) corneas is so inhibited.